Method of making calcium carbide



Aug. 16, 1932,. A. o. WILLIAMS METHOD OF MAKING CALCIUM CARBIDE INVENTR Aud lexj O` Williams ATTORNEY 1I l II ...IULM III,

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.HTL I fio UNITED-STAT ES Patented Aug. 16, 1932 GASN' CYANAMID COMPANY, OF NEW YORK,'N. Y., A CORPORATION OF MAINE `Mnrnon or i MAxrNe oALcIUM cAnBIDE Application led September Abeing fedV into uan electric arc furnace where Athe high `temperature melts the two ingredients and causes them to combine with the formation of calciumcarbide which contains other substances; because of an incomplete reaction andbecause of the presence in the raw materials of various impurities. has

been found thatAth-efraw materials for the making of calcium carbide should be in granular' form or in particles of relatively large size, because iine material is not acted upon by theheat of the electric furnace but is blown out of the topl thereof by the generation of gases in the .reactionzone. It has been conservatively estimated that the amount of material thus lost in the form of dust constitutes `8% to 10%4 of the total vamount of material going into the furnaces.

A The present invention is intended to obviate this loss of raw materials, it being among y the objects thereof to provide a modification y of the methodof making calcium .carbide whereby the Waste of raw material is minimized.'` i i q p It is also among the objects of this invention toprovide a method in which ne material is utilized and is fed into the `furnace ina modified form and the eiiciency of the furnace increased thereby. l.

VIn practicing my invention I remove `iine material ordust from .the lime andfrom the coke, and also `from the lime and coke mixturew-hich is fedto the furnace. Part or all of the lime dust thus obtained is treated `with water to form a solution of lime or lime water, whichwis then used` as a Ybinder for :coke dust or a mixtureof lime dust and coke dust` relatively large percentage of lime incorporated in the mixture vand I utilize atleast of' lime but I may use up to 1,1926. sensi No. 133,022.

AimLnY o WILLrAMs, or NIAGARA FALLS, oNrARIo, .cANAnAAssIGNoR .To AMERI- and over 35% thereof. The plastidmass formed in the mixture is `extrudedfrom a suitable press and is cut up into briquets of suitable size which are placed upon trays or pallettes and dried, preferably in an oven at a relatively lowtemperature, sulicient only to drive off` the excess of water in the briquets. Inv some cases/I may `provide such a proportion of lime dust "to coke dust in the briquets that the briquets constitute a complete charge' for the furnace and they are therefore fedinto the furnace without any additions of other materials and smelted down tolformcalcium carbide. However, in n most casesIL have found it to'be more convenient, principally because the `amount -of coke dust formed is considerably greater than the amount of lime dust formed,

to make a briquet; containing, say,A %V V V,to limeand 70% to 75% of coke dust and'add 4to briquets fof this kind a sulficient amount ofgranular or lump ,lime to provide the proper portion of ingredients Qfor makingcalcium carbide. Furthermore, I may add to such a mixture additional gran- 'ular lime and coke to increase the amount of Ycharge for the furnace whereby` the briquets constitute but a small fraction of the charge instead of constituting all or the major portion thereof.' V l q In the accompanying drawing constituting a part thereof andin which like reference characters indicate like parts:

Fig. `1 is a planview, somewhat diagrammatic, showing an apparatus adapted for carrying out the briquetting portion of my method; andwith a drying unit adjacent thereto. Y y 1 Fig. 2 is afragmentary, side elevational view of the oven used for drying the briquets, an g Fig. 3 is an enlarged, perspective view of a tray or pallette for holding the briquets during one stage of the operation.

There is provided a bin 1 for lime dust having aV connection with a tank 2, containing a stirrer 3, whereby lime dust from the bin l may be mixed with water to provide the lime water binder which is then forced by pump las Y The slices. 17 may be further cutvinto sections 28..gasshown most clearly in Fig. 3,V andthe veyor type.

mixer 7, containing a rotating lstirrer `8f of chine,.fthe material issuing'fromthe nozzle. 14 in therformof a rod 15-wliich movesV alongthe cutting table 16. An'operator cuts the rod 15 into slices `17 which are'placed" upon Vthe "pallettes 18, which are formed `with downwardlyextending edges 19 for rigidity.

pallettes 18 -are placed' upon endless Vcon- .veyor belty20. and are movedjrthereby `to 1 the proper curingoven :The drying apparatus 1 for the l sists of aseriesof ovens 21 provided with Y va furnace 22 onone end thereof, the-.prod- Au cts of combustion of the furnace passing successively through the several ovens and zout through stack 23 at theopposite end of the apparatus. Each of the ovens is'provided with as sliding `door `24 )in the .front thereof, the said door beingrmounted on counter-,weightedchainsA25 passing over pulleys 26.v VThe ovens arex'further provided -withra series c of j's'paced' ledges 27 forthe re- YVception of the trays or pallettes 18. Y

In theoperation of myimethod I mayffirst ,providela -`binder of lime water in the tank v 2and.v feed` the'same through pipes 5 and 6 Lto"mixer 7 where ian operator sprays 4the .binderlkupon the ymaterial .being agitated in thesaid mixer. :Thismaterial may 'be coke dustfrom bin 9 which isfed by meansof :conveyor .11 and chute 12to the mixer 7 for it maybe amixture of coke dust and lime dust from th'epbin 10 or itmaybe material in suitable proportions from both bins 9 and V10. The proper amount of lime water for .the making of the briquetsv is gauged-by the '.opgerator atjthe mixer andis added thereto as the dust passes'through the same. .s The plasticmass thusformed-therein is thenjextrudedonto the cutting table -16.where an Y operator,cuts off sections' therefroml with a .blunt knife :andplaces them vonV `the pallettes 18. VHe may also cut each individualsection t17. into four Yparts 28 V.so `that the individual briquets may be .of smaller sizetoffacilitate subsequent drying and handling. l/Vhen-a .-pallette 18 ,hasl..beenV covered with sections it .is placed on the endless belt v20 and it travels toa point opposite-the oven/to be ,l1ed, where: one or `more operators removes VV. thesa'me.andp'laces it within the oven, as

shown'in Figuresl and 2.V Whenan oven has-been flled,}the door 24 isclosed and the jointsor cracks'v areflled with a plastic mixf '.tureysuch as c1ay,in'order @to prevent leakage Yreason of charging'into the furnacefmaterial the furnacewithout'any additions thereto,

sirab-letol add granular lime or coke or both t6 vcomplete the furnace charge. For ex-k ample,fif about 25%` to 27% ofvlime has .been incorporated into the briquetsitis necessary to add,800 pounds'of granular lime to each 1,000r pounds of briquets in order toobtain the: ,correct Vproportions for they,` furnace charge. v

*7: By my'method. ofbriquetting the lime. dust and coke duvstI have been ablek to add7% to 8% tothe amountvof carbide` produced from a given amount ofv raw material by which had Apreviously gone to waste. The

"but generally, as rvexplained above, it is decost4 of the operationofbriquetting is rather Y low and I nd that IY obtain a net saving of about $6.00 per tonof'dust briquetted` Not only do I save wastematerial but more important still is the result Vofusing `this materal on the operation ofthe furnace itself.

I have found thatthe briquetted material is `more effective than the loose granular mate- `rial and ineswhich had hitherto been exclu;- sively usedin the furnace. It would appear` that in a briquet thereis a more vintimate con'- tact between the particles of lime and coke, giving a quicker reaction therebetween, causing the. fusion to take placeat a higher VV'rate and making the operation of the furnace smoother and less subject to'liuctuations, 4 I have found that one ton of briquets produces as much calcium carbide as about 1.1 tons of the ordinary granular Aand lines Y mixture. Furthermore, the making of a ton of carbide from thebriquets requires abo-ut54% to 6% less power than that necessary to form the same` amount of carbide from the old granular and fines mixture.,` By thejuse ofbriquets less material is blown out of the furnace in the formofdust.

It has always been considered essential that the lime used in al carbide furnacebe perfectlyanhydrous in `order to avoid the waste of electrical energy required for driving lolfl the water from the lime. `My briquets contain a considerable amount of water combined with the lime but I find that in the use thereof no additional energy is necessaryA as Water is given olf from the hydrated lime' at a temperature of about 4150"V C. which occurs at .the top of the furnace where the material is fed in. The heat utilized for removing the water that the lime may be the major constituent is Waste heat which ordinarily is radiated and 1ost.`

Although I have described my invention,

"setting forth a specific procedure and appal ratus for producing briquets which are used in the furnace for making calcium carbide, it

is apparent that my invention is not limited to the details mentioned as various changes may be made therein within the scope of this invention. For instance, I may change the.

`proportions of lime to coke in the briquets so M zand I may add coke to the briquets in the furnaceoperations to provide the proper proportions of raw materials. The several steps in the production of the briquets may be diii'erent from those outlined, as for example, the briquetsmay be dried in the air or may be continuously fed through a tunnel kiln and thence directly into the furnace. Y The drying ofthe briquets may take place, at least par- Htially, at the to-p ofthe furnace as they are fed towards the reaction zone.

lInstead of hand operations in the mixing of the plastic mass and the extruding and cutting of the briquets, I may substitute automatic machinery for this purpose. Instead of feeding lime Water directly from the mixer 2 through pipes and 6 by means of pump 4, I may utilize a storage tank at a high level into which the lime Water is pumped and fro-m which it may be fed bygravity tothe mixer 7. lThese and other changes may be made in my invention, the scope thereof being defined in the claims appended hereto.

What Iclaim is: n

1. A method of making calcium carbide which comprises providing a mixture of coke,

`lime andwater, forming briquets therefrom, drying the briquets and smelting the same together-With additions of lime and coke.

2." A `method of making calcium carbide which comprises providing a mixture of coke dust, lime dust and water, forming briquets therefrom, drying the bri uets and smelting the same together with ad itions of lime and coke.

In testimony whereof, I have hereunto subscribed my name this 30th day of August,

AUDLEY O. WILLIAMS.

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